This application claims the priority of German patent document 100 26 246.5, filed 26 May 2000 (PCT No.: PCT/EP01/05435), the disclosure of which is expressly incorporated by reference herein.
This case is related to co-pending U.S. patent application Ser. No. 10/296,344 filed Aug. 15, 2002.
The invention relates to a method for exchanging data between a plurality of subscribers which belong to different data bus systems.
Modern vehicles frequently include several (preferably standardized) data buses. For engine and chassis components, for example, one system is used which is adapted to that application, while another suitably designed bus system is used for audio and telecommunication peripheries. Data exchange between the different bus systems takes place by way of a plurality of gateways.
An attempt to transfer this bus system architecture which is used in higher-priced vehicles to vehicles of lower cost, however, results in high expenditures, due on the one hand, to the high costs of the standard bus for engine and chassis components and, on the other hand, to the cost of a gateway which are high because of the computer required for this purpose. The construction of a separate onboard network structure for lower priced vehicles is problematic in that it is largely impossible to take over individual components of the higher-priced vehicles because of a lack of compatibility. In addition, a conflict arises due to differing goals. For lowering the cost, the transmission rate can be reduced and the number of bus subscribers can be increased, which results in long response times and low flexibility, because subscriber numbers differ from one vehicle to the next. Every addition of a new subscriber (for example, as a result of a subsequently installed component) requires considerable adaptation expenditures.
It is an object of the invention to provide a highly efficient method of exchanging data among the subscribers of different data bus systems which can serve a plurality of subscribers that vary in a vehicle-specific manner.
The method according to the invention is modular and cost-effective. It permits the use of the same basic components in all vehicles covering several model series of a manufacturer. The higher-quality vehicles can be arbitrarily equipped with additional components, without being more expensive than comparable series systems.
A prerequisite for the invention is the existence of a faster data bus, such as for example the data bus described in German Patent Documents DE 19636441 A and DE 19636442 A. This data bus is distinguished by a transmission rate of more than 5 Mbits/s and is suitable, for example, for passive safety systems, such as air bags, belt tighteners, and the like, as well as the pertaining sensor system and actuators and their control units.
The control units are situated at different points of the vehicle (for example, in the area of the transmission tunnel or the B-columns, in the door or at the steering column). All such control units are connected with the data bus which, in normal situations (that is, outside a crash phase or serious misuse phase), is not utilized to a great degree. The same applies to the utilization of the processors in the control units.
According to the invention, these control units are also used for other functions. These functions are part of different function peripheries, for example, on the one hand, the electronic system of the vehicle body, and relate, for example, to the light control, the wiper control, the central locking system and the window lift mechanism control, and, on the other hand, the data bus systems for engine and chassis components.
Instead of a gateway for the transition between the data bus systems, the gateway functionality is apportioned to the two control units of the faster data bus, which already exist anyhow, with the possibility of achieving a required computing performance by means of the computer which is already present in the control unit.
In addition, it becomes possible to divide each of the two data bus systems into smaller subordinate data bus systems which each, by way of one of the control units connected to the faster data bus, feed their data to this data bus or take it over from the latter.
Thus, the periphery of the electronic system of the vehicle body can be divided into the light control and the wiper control, on the one hand, and the central locking system and the window lifter control, on the other hand. These are each a component of a subordinate data bus system which, in each case, because of the minimized number of subscribers (in the case of the light control, for example, one control unit and connected consuming devices), has a satisfactory response time and is also operable at a low transmission rate; that is, rapidly and securely provide the connected subscribers with the required data, or cause them to be provided with the required data. As a result, it is also possible to connect control units the electronic system of the vehicle body or of the engine management (with higher demands on the communication), directly to the faster data bus.
With such an onboard network system structure, the need for a separate data bus for the components of the electronic system of the vehicle body is eliminated, because these components are connected to the faster data bus, either directly or via otherwise existing, control units. This results in the elimination of the gateway functionality and thus of separate gateways.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.